JPS58222931A - Fuel supply device - Google Patents

Abstract

PURPOSE:To obtain a stable speed of an engine at its idling time, by performing fuel injection at a fixed frequency at the idling time in a fuel injection device synchronously injecting fuel with the speed of the internal-combustion engine at its normal operation. CONSTITUTION:In a fuel injection timing control circuit 28, a synchronous signal of injection is selected by a pulse frequency selector circuit 29. When speed of an engine is in a range of frequency corresponding to a prescribed speed containing an idling speed, a frequency comparator circuit 30 generates an on-signal to a control circuit 31. When a signal of a pressure sensor 12 is an intake pipe pressure at idling operation, a voltage comparator circuit 37 outputs an on- signal. A signal of an idle switch is input to a selection control circuit 31 in addition to both output signals of the circuits 30, 37, when all signals are on, the circuit 29 is operated, and the signal is selected from a signal synchronized with the speed to a signal of a fixed frequency pulse generator circuit 32.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a fuel supply for an internal combustion engine (hereinafter also referred to as engine) in which fuel regulated to a constant pressure is metered by opening/closing control of a solenoid valve by an electronic control circuit and injected into an intake passage. It concerns the fetal apparatus.

Conventionally, in fuel metering control using a solenoid valve, an injection control signal is generated using a frequency pulse signal synchronized with the rotation of the engine and a pressure signal corresponding to the pressure in the intake pipe, and the injected fuel is metered by controlling the opening and closing of the solenoid valve. It had been. With this method of fuel supply, optimal fuel control is possible while driving when the engine speed is high, but when the engine speed is low and idling, it is difficult to record the engine speed and determine the amount of fuel supplied. Not stable. In other words, since fuel is supplied according to the fluctuation of the engine's rotation, the amount of fuel that is different from the amount required by the engine at that time is supplied.
This increases the rotational vibration of the engine. Therefore, in order to maintain stable engine rotation, the engine speed during idling must be set to a high value, leading to a worsening of fuel consumption.

In order to solve the above-mentioned problems, this invention stabilizes the rotation of the engine during idling, sets a low idling speed, improves fuel consumption rate, and provides a vehicle with a good feeling. The purpose is to provide an electronically controlled fuel supply system for internal combustion engines.

This invention will be explained based on drawings of embodiments.

In FIG. 1, 1 is an engine, 2 is an intake pipe, and 6 is a fuel supply device. In the fuel supply system 6 , 4 is a throttle body whose upper end is connected to an air cleaner (not shown), and whose lower end is connected to the intake pipe 2 and continues to the engine 1 . The inside of the throttle valve f-4 is an intake passage 5, and a valve housing 7 supported at the tip of a fuel passage 6 is provided at the intake passage 5. A solenoid valve 8 driven by an electronic control circuit 10 is installed inside the valve housing 7, and a fuel nozzle μ opens at the bottom of the figure. The upstream portion of the fuel passage 6 is a slot! - It is fixed through the side wall of the body 4 and introduces fuel supplied from a fuel pump (not shown) to the solenoid valve 8. A throttle valve 9 is provided at the bottom of the intake passage 5. The throttle sensor 11 works in conjunction with the throttle valve 9 to detect changes in throttle output. A pressure sensor 12 that detects pressure and an intake air temperature sensor 15 that also detects temperature are installed in the intake pipe 2.

A water temperature sensor 14 for detecting the temperature of the engine is attached to the engine 1, and an air-fuel ratio sensor 15 for detecting the concentration of oxygen 51 in the exhaust gas is attached to the exhaust pipe 16.

Here, the conventional configuration of the electronic control circuit 10 will be explained with reference to FIG. The rotation speed sensor 17 is an electromagnetic pickup type that detects passage of a protrusion provided on the crankshaft of the engine. However, other types, such as a combination of a magnet with magnet pieces and a Hall element, are also suitable. The signal from the rotation speed sensor 17 passes through the waveform shaping circuit 19 and is input to the basic calculation circuit 20 together with the signal from the pressure sensor 12 of the intake pipe 2, and the basic energization bus width Tp is determined. The waveform shaping circuit 19 may be a known one (for example, a Schmitt circuit). Each signal detected by the throttle sensor 11, pressure sensor 12, and water temperature sensor 14 is
The signal is input to the correction circuit 21 and subjected to arithmetic processing. Basic calculation circuit 20. The signals from the intake air temperature sensor 16, the water temperature sensor 14, the air-fuel ratio sensor 15, and the correction circuit 21 are processed by the multiplication circuit n to create the current flow width Tm.At the same time, the pulse width Tm is An injection correction pulse width Tv is generated by a pulse generation circuit 26 that generates an injection correction pulse using the voltage of the battery 18 in synchronization with the cut-off timing.The energization pulse width Tm and the injection correction pulse width Tv are The injection pulse width T
It becomes an injection pulse signal of = T m + T v, is amplified by the output circuit 25, sends a valve opening signal synchronized with the rotation of the engine 1 to the electromagnetic valve, opens the nozzle μ, and injects the fuel while metering it. With the configuration of a conventional fuel supply system, when the engine 1 is idling, the rotation fluctuates, so if the fuel metering is controlled using a pulse number synchronized with the rotation, the rotation speed will fluctuate when the rotation speed swings toward the higher side. The number of pulses increases, the amount of fuel increases, and the rotational speed becomes higher. On the other hand, if the rotation speed swings to the lower side, the color will become even lower rotation speed. Furthermore, since a signal from a pressure sensor is input to the basic calculation circuit 20 along with a waveform determined by the rotational speed, fluctuations in the injection control signal are further increased due to the influence of fluctuating pressure in the intake pipe.

If the rotational speed fluctuates greatly like this, stable idling rotation cannot be obtained.

Next, an embodiment according to the present invention will be described with reference to FIG. FIG. 5 shows an arithmetic circuit including a control unit 26,
This is a modification of the conventional part in which the signal from the rotation speed sensor 17 is input to the basic arithmetic circuit 20 together with the signal from the pressure sensor 12 via the waveform shaping circuit 19.

The control unit 26 consists of an idle switch 27 and an injection timing control circuit 28 , and inputs signals from the rotation speed sensor 17 , idle μ switch 27 , and pressure sensor 12 to the control circuit 28 , and inputs signals to the basic calculation circuit 20 . Outputs two signals. Id μ・sui y f 27 n
, 2 I:1 y) IV /"w"907'"9
'1, ;.

Any known on/off switch may be used. An embodiment of the injection timing control circuit 28 is shown in FIG.

The waveform shaping circuit 19 inputs the signal from the rotation speed sensor 17 and outputs the signal to the pulse frequency switching circuit 29 and the frequency comparison circuit 60. The switching control circuit 61 includes a frequency comparison circuit 50, an idle switch 27, and a voltage comparison circuit 6.
By inputting each signal from 7, the pulse frequency switching circuit 29
and output signals to the voltage switching circuit 66, respectively. The signal from constant frequency pulse generation circuit 62 is input to pulse frequency switching circuit 29 . A signal is output from the pulse frequency switching circuit 29 to the basic arithmetic circuit 20. pressure sensor 1
The signal from 2 is sent to the voltage switching circuit 66 and the voltage comparison circuit 6.
7 is input. The voltage switching circuit 66 is the switching control circuit 6
1. Manually input each signal from the pressure sensor 12 and the constant voltage generation circuit 68 and output the signal to the basic arithmetic circuit 20.

FIG. 5 shows an injection timing control circuit 40 of another embodiment. The difference from FIG. 4 is that the constant frequency pulse generation circuit 62 is not provided, and instead, the waveform shaping circuit 19 is replaced by an FV conversion circuit 66,
A circuit is formed which connects to the pulse frequency switching circuit 29 through the averaging circuit 54 and the VF conversion circuit 65. Further, there is no constant voltage generating circuit 68, and instead a circuit is formed that connects the pressure sensor 12 through an averaging circuit 69 to a voltage switching circuit 66. The averaging circuits 54 and 59 may be constructed from known capacitors.

FIG. 6 shows an example of a circuit diagram of the injection timing control circuit 28 (FIG. 4). The frequency comparison circuit 30 includes an FV conversion circuit 36, resistors 41a, 41b, 42a, 42b, voltage comparators 45, 46, etc., and outputs the input from the waveform shaping circuit 19 to the switching control circuit 31. The voltage comparison circuit 67 includes resistors 43a, 43b, 44a, voltage comparators 47 and 48, and outputs the input from the pressure sensor 12 to the switching control circuit 61. The constant frequency pulse generation circuit 52 may be a known clip-flop circuit, and the pulse frequency switching circuit 29 and the voltage switching circuit 66 may have a known circuit configuration as shown in FIG.

In the fuel supply device 5 configured as described above, when the engine 1 is in a load operation state, the control unit 26 shown in FIG. Intake pipe 2 (Fig. 1)
Optimum fuel control is performed by inputting a signal from a pressure sensor 12 that outputs a voltage corresponding to the pressure of the engine.

When the engine 1 is idling, a pulse frequency corresponding to a constant rotation speed and a voltage corresponding to a constant intake pipe pressure are output to the basic calculation circuit 20. That is, in the injection timing control circuit 28 in FIG. . This frequency comparison circuit 60 outputs an ON signal to the switching control circuit 61 when the engine speed is in a frequency range corresponding to a predetermined speed range including the idling speed. Further, the pressure sensor 12 is connected to the intake pipe 2.
A voltage corresponding to the pressure is outputted to the voltage switching circuit 66 and simultaneously outputted to the voltage comparison circuit 67. This voltage comparison circuit 67 outputs an ON signal to the switching control circuit 61 when the signal from the pressure sensor 12 indicates a predetermined pressure range including the pressure in the intake pipe 2 during idling. Switching control circuit 61
inputs the signal from the idle switch 27 in addition to the above 12 signals, and when these five signals are on, outputs an on signal to the pulse frequency switching circuit 29 and voltage switching circuit 56. At this time, the pulse frequency switching circuit 29 outputs a constant frequency pulse waveform from the constant frequency pulse generation circuit 52 to the basic arithmetic circuit 20, and at the same time, the voltage switching circuit 66 outputs a constant voltage from the constant voltage generation circuit 68 to the basic arithmetic circuit 20. Output to.

In the injection timing control circuit 40 shown in FIG.
To the idling pulse frequency switching circuit 29, the signal from the waveform shaping circuit 19 passes through an FV converter 66, the frequency of which is converted into a voltage, and this voltage signal is averaged by an averaging circuit 64. When the voltage signal thus obtained passes through the VF converter 65, the pulses with large frequency fluctuations of the waveform shaping circuit 19 are input as a pulse signal □l having an averaged frequency. At the same time, the highly variable signal from the pressure sensor 12 passes through the averaging circuit 39, becomes an averaged voltage signal, and is input to the voltage switching circuit 66.

The injection timing of the embodiment shown in FIG. 4 is shown in FIG. 7. FIG. 2(A) shows instantaneous pressure fluctuations in the intake pipe 2 when the engine is in an idling state, using the output of the pressure sensor 12. Figure (b) shows the instantaneous engine speed. In (a) and (b), the solid line is the conventional example (
Figure 2). That is, the intake pipe pressure and engine speed fluctuate in a wave-like manner. Here, set the idling speed to 60 rpm.

Even if the intake pipe pressure at that time is -54011IHg,
When controlled by a conventional control circuit, the synchronous injection state shown in FIG. In other words, the timing intervals and widths become inconsistent. On the other hand, in the embodiment of the present invention shown in FIG. 4, when the engine 1 is in an idling state, the pressure sensor output 1.0, which corresponds to, for example, the intake pipe pressure 540 Hg. O
If V is set in the constant voltage circuit 68 and at the same time the flip-flop oscillation number 20) f, which corresponds to an engine rotational speed of 600 rpm, is set in the constant frequency pulse generation circuit 62, an on signal is generated from the switching control circuit 51. When entering, 20Hz, 1
．． 0V constant periodic constant pressure injection is performed. This timing is constant as shown in Doshinzu. When the engine revs oscillates and tries to rise, the revs do not increase because the fuel does not increase accordingly, and when the revs try to drop, the situation is similar to that of an increase in fuel, so the revs must be maintained. work. In this way, the idling rotation of the engine 1 is in a very stable state with little vibration, as shown by the chain line in FIG.

FIG. 8 shows the injection timing of the embodiment of FIG. The solid lines in (a) and (b) of the same figure are the conventional control separation diagram (Fig. 2)
This is the case when controlled by When this is controlled according to this embodiment, timing corresponding to the average rotation speed of the engine 1 can be obtained by passing the rotation speed of the engine 1 through the FV conversion circuit 65, the averaging circuit 64, and the VF conversion circuit 65.

Furthermore, by passing the output of the pressure sensor 12 through the averaging circuit 69, an output corresponding to the average pressure of the intake pipe 2 can be obtained. When a signal is input from the switching control circuit 61 due to such an output, average cycle average pressure injection is performed at the timing shown in FIG. The figure shows that the engine speed is 10 rpm and the intake pipe pressure is, for example, set value 600 rPm, -54 rPm.
deviated from offgug, 610 rpm, -5 respectively
This shows the case where the pressure reaches 450Hg.

On the other hand, according to the embodiment shown in FIG. 5, the average rotational speed of the engine 1 is 610 rpm and the average intake pipe pressure is 545 mHg.
Since the fuel is metered with the same injection timing and width,
Even if the rotation speed deviates slightly, as long as it is within the upper and lower limits of the set rotation speed and intake pipe pressure, as in the case of Fig. 7, suppress the rotation speed from rising and hold it from falling. As shown by the chain line in FIG. 8(b), the vibration of the engine at the time of pilling is made very small. That is, in the embodiment shown in FIG. 5, even if the average value deviates somewhat from the idling setting value, stable fuel metering can always be performed in accordance with the average rotation speed.

As explained above, the present invention provides a fuel supply device that measures and injects fuel regulated to a constant pressure into an air supply passage by controlling the opening/closing of a solenoid valve by an electronic control circuit. outputs an injection pulse signal that corresponds to the rotation of the engine and the pressure of the intake pipe, and when idling, it outputs an injection pulse signal that corresponds to the actual rotation speed, and instead outputs a frequency that indicates a constant or average value of the engine rotation speed and the actual intake pipe. By installing a control unit that switches and outputs an injection pulse signal stabilized by a constant or averaged voltage instead of the pressure of It is possible to stabilize the rotation of the engine, and therefore, it is possible to set the idling speed to a low value, thereby reducing the fuel consumption rate and improving the feeling and ringing during idling.

[Brief explanation of drawings]

Figure 1 is a simplified longitudinal cross-sectional view of the entire fuel supply system including the engine.
FIG. 2 is a block diagram showing a conventional electronic control circuit, FIG. 6 is a block diagram showing a control unit of an electronic control circuit according to an embodiment of the present invention, FIG. 4 is a block diagram showing an injection timing control circuit, and FIG. Figure 1 is a block diagram showing another embodiment of the injection timing control circuit, Figure 6 is a circuit diagram of the injection timing control circuit, and Figures 7 and 8 are explanatory diagrams showing injection timing and its effects. be. 8... Solenoid valve 10... Electronic control circuit 1
2...Pressure sensor 17...Rotation speed sensor 1
9...Waveform shaping circuit 20...Basic calculation circuit 26
... Control unit 27 ... Eye trip switch 28.40 ... Injection timing control circuit 29 ...
・Pulse frequency switching circuit 60...Frequency comparison circuit 3
1...Switching control circuit 62...Constant frequency pulse generation circuit 66...FV conversion circuit 34.39...
Averaging circuit 65...VF conversion circuit 66...Voltage switching circuit 67...Voltage comparison circuit 68...For constant voltage generation circuit Applicant: Aisan Industries Co., Ltd. Agent Patent attorney Hidehiko Okada

Claims (3)

[Claims] (1) A fuel supply device for an internal combustion engine that measures and injects fuel, which is pressure-fed by a fuel pump and adjusted to a constant pressure by a regulator, into an intake passage by controlling the opening and closing of a solenoid valve by an electronic control circuit, During load operation, the control circuit outputs a frequency pulse signal from the rotation speed sensor that is synchronized with the rotation of the internal combustion engine and a pressure signal from the pressure sensor that responds to the pressure in the intake pipe. A fuel supply device characterized by having a control unit that can switch between and output a frequency pulse signal generated at a constant frequency and a pressure signal generated at a constant or almost constant voltage from a voltage generation circuit. (2) The control unit transmits an on/off signal of the idle switch, a signal output from the rotation speed sensor of the internal combustion engine via a waveform shaping circuit and a frequency comparison circuit, and a signal output from the pressure sensor of the intake pipe via the pressure comparison circuit. a switching control circuit that outputs a switching signal in parallel with the signal output from the rotation speed sensor, and a frequency pulse signal and constant frequency pulse synchronized with the rotation of the internal combustion engine output from the rotation speed sensor via a waveform shaping circuit. A pulse frequency switching circuit that switches one of the constant frequency pulse signals generated from the generation circuit by a switching signal from the switching control circuit and sends it to the basic arithmetic circuit; The switching control N controls either the pressure signal in response to the pressure change or the constant pressure signal generated from the constant voltage generation circuit.
2. The fuel supply device according to claim 1, further comprising a sensor voltage switching circuit that switches in response to a switching signal from the road and sends the switched voltage to the basic arithmetic circuit. (3) The control unit outputs an on/off signal of the idle μ switch, a signal outputted from the rotational speed sensor of the internal combustion engine via a waveform shaping circuit and a frequency comparison circuit, and a pressure comparison circuit from the pressure sensor of the intake pipe. a switching control circuit that outputs a switching signal by receiving in parallel a signal output from the rotation speed sensor through a waveform shaping circuit, and a frequency pulse signal synchronized with the rotation of the internal combustion engine output from the rotation speed sensor via the waveform shaping circuit; Pulse frequency switching for switching between a frequency pulse signal obtained by roughly averaging the pulse signal through an FV conversion circuit, an averaging circuit, and a VF conversion circuit using a switching signal from the switching control circuit and sending the signal to the basic arithmetic circuit. The switching control circuit similarly controls either the pressure 1M output from the pressure sensor in response to a pressure change in the intake pipe or the pressure signal obtained by averaging this pressure signal via the averaging circuit. 2. The fuel supply device according to claim 1, further comprising a sensor voltage switching circuit that switches and sends the switching signal to the basic arithmetic circuit according to a switching signal from the sensor voltage switching circuit.